<!--
 * @: 
 * @Version: 1.0
 * @Autor: ziwei
 * @Date: 2022-03-10 09:49:01
 * @LastEditors: ziwei
 * @LastEditTime: 2022-03-10 10:04:12
-->
<html>
    <head>
        <style>
          *{
              margin: 0;
              padding: 0;
          }

          #container{
              width: 100px;
              height: 100px;
              z-index: 1;
          }

          .main{
              background: red;
          }
          #hello{
              background: green;
              width: 100px;
              height: 100px;
          }
          #world{
              background: blue;
              width: 100px;
              height: 100px;
          }
          #absolute{
            background: pink;
            width: 50px;
            height: 50px;
            top: 0;
            left: 0;
            z-index: 9;
          }
        </style>
    </head>
    <body>
        <div id="container" class="main"></div>
        <div id="hello" style="color: blue;">hello</div>
        <div id="world" style="display: none;">world</div>
        <div id="absolute" style="position: absolute;">abs</div>
    </body>
</html>